Many two-piece solid golf balls are known in the art. As compared with the wound golf balls, the two-piece solid golf balls have the advantage of an increased total flight distance on both driver and iron shots, because of a so-called straight liner trajectory and a low spin receptivity due to their structure, which allows for a long run. On the other hand, the two-piece solid golf balls are more difficult to control than the wound golf balls in that they do not stop short on the green because of low spin receptivity on iron shots.
Like flight distance, a soft feel when hit is essential for golf balls. The absence of a soft feel represents a substantial loss of commodity value. As compared with the two-piece solid golf balls, the wound golf balls have the structural characteristics ensuring a soft and pleasant feel.
On two-piece solid golf balls consisting of a core and a cover, attempts have been made to soften the ball structure in order to accomplish a soft feel upon impact. A soft core is often used to obtain such soft-feel two-piece solid golf balls, but making the core softer lowers the resilience of the golf ball, compromises flight performance, and also markedly reduces durability. As a result, not only do these balls lack the excellent flight performance and durability characteristic of ordinary two-piece solid golf balls, but they are often in fact unfit for actual use.
Various three-piece solid golf balls in which an intermediate layer is situated between a solid core and a cover have been proposed to resolve these problems as disclosed, for example, in JP-A 7-24084, JP-A 6-23069, JP-A 4-244174, JP-A 9-10358, JP-A 9-313643, U.S. Pat. Nos. 4,431,193, 5,733,206 and 5,803,831.
Golf balls having the cover and the intermediate layer made soft according to these proposals have a soft feel, but a shorter flight distance on full shots with a driver. To insure distance, the cover and the intermediate layer must be formed hard at the sacrifice of the feel upon approach shots and putting. The spin performance on iron shots is also aggravated.
Although a number of proposals have been made for finding a good compromise between increased distance upon full shots with a driver and ease of control upon approach shots as discussed above, many golfers desire a further increase of distance. None of prior art solid golf balls fully meet the demands.